The disclosure relates to a rotor for a rotary tablet press with a washing device, with an upper-punch guide ring having guides for upper punches, with a lower-punch guide ring having guides for lower punches, and with a die plate arranged between the punch guide rings, wherein at least one sealing element which interacts with the associated punch can be fastened or is fastened in or to the guides for the upper and lower punches. The disclosure furthermore also relates to a rotary tablet press with a housing, with a rotor which is arranged in a drivable manner in the housing and has an upper-punch guide ring with guides for upper punches, a lower-punch guide ring with guides for lower punches and a die plate arranged between the punch guide rings, and is provided with sealing elements assigned to the upper and lower punches, and with a washing device with which the rotor can be washed or can be cleaned by means of washing liquid.
Rotary tablet presses having upper and lower punches, which are guided in associated punch guide rings and with which tablets, in particular made of powder, such as tablets for medicaments, washing-agent tablets or the like can be produced in the dies of a die plate, have long been known. The rotor which is driven by means of a suitable motor can have, for example, up to 60 pressing stations and can revolve at speeds of, for example, up to 150 rpm depending on the size and diameter of the punch guide rings and die plate. The upper and lower punches here are moved up and down by means of suitable rollers or slotted guide tracks in order to undertake the production of the tablets in the dies. In order to protect the guides for the punches, which guides are generally designed as sliding guides, from the entry of dust from the tablets, the upper and lower punches are assigned sealing elements which can be designed as expansion bellows, as disclosed, for example in WO 02/064 356 A1, or as sealing collars with stripping lips, as disclosed in WO 03/084 738 A1.
In the case of more recent generations of rotary tablet presses, use is made of washing devices which are integrated therein and with which the rotor and also the entire working interior in which the rotor is located during operational use can be cleaned with washing liquid. The integration of automatic washing devices permits short conversion times to a different tablet geometry while maintaining high operational reliability. The washing liquid is sprayed into the working space at a pressure of, for example, up to 6 bar via nozzles, and the surfaces of the punches, and the dies and/or receptacles for the dies are cleaned with the washing liquid under pressure. Since all of the parts coming into contact with the product to be produced are cleaned with the washing liquid, contamination of a subsequent batch can be prevented and at the same time the risk to personnel from dust from the tablets, the dust being detrimental to health, is avoided. However, in the case of rotary tablet presses with a washing device, there is the risk that the washing liquid will also penetrate into the sliding guides for the punches, as a result of which, under some circumstances, costly work to reclean the rotary tablet press may be necessary.
It is the object of the disclosure to improve a rotary tablet press and the associated rotor structurally for the use of an automatic washing device.
This and further objects are achieved according to the disclosure with the rotor and the rotary tablet press in that a leakage passage for discharging the washing liquid is formed for each lower-punch guide in the lower-punch guide ring. The leakage passages are preferably intended only to carry out their discharging function whenever leakages occur unnoticed at individual sealing elements of the lower-punch guides. Owing to the leakage passages provided according to the disclosure, even leakages of individual sealing elements do not then lead to damage to the guides in the lower-punch guide ring and/or to contamination of an oil or machine sump with washing liquid, such as in particular water.